The present invention relates to a diamond gauge which enables the user to determine what size diamond will fit in a given setting without the need to manipulate the diamond itself.
In the preparation of jewelry, it often becomes desirable to incorporate a pluarality of relatively small diamonds in the jewelry design. These diamonds may provide an appropriate framing or setting for one or more larger stones or may themselves form a design independent of any larger stones. Such small diamonds are held in place by settings which typically include a plurality of prongs although other types of settings are known. Before placing the diamonds in their settings, a determination must be made as to the size of the diamond which will fit into a given setting. This process becomes quite difficult when sizing relatively small diamonds ranging from 1/2 point (1/200th of a carat) up to approximately 50 points (50/100ths of a carat).
To better understand this procedure, the manner in which a round diamond is set in a standard four-prong setting will now be described with reference to FIGS. 1-3. While reference is made to a diamond and a four-prong setting, it will be understood that the present invention is useful in connection with other stones and with settings other than a four-prong setting.
Small diameters are normally cut in a round shape known generally in the art as a brilliant cut. This shape is illustrated in FIG. 1. As shown therein, the diamone 10 has a plurality of star facets 12 extending at an angle between a flat table 14 and a girdle 16. The girdle represents the radially outmost portion of the diamond and is the portion of the diamond which is primarily supported by the setting. A plurality of depending facets 18 extend downwardly from the girdle 16 and terminate at a culet 20 defining the bottom point of the diamond.
The shape of a standard four-prong setting is illustrated in FIGS. 2A and 2B. As shown therein, the setting 22 includes four prongs 24 which extend upwardly and outwardly from a common base 26. Each of the prongs 24 terminates at a respective top end 28.
As best shown in FIG. 3, before the diamond 10 is placed in the setting 22, a small ledge 30 is cut in each of the prongs 24. The ledge 30 is formed by filing a small indentation in each prong 24 slightly below the end 28 of the prong. The diamond 10 is then placed in the setting 22 such that the top of the depending facets 18 located immediately below the girdle 16 sit on the ledges 30. Thereafter, the tips 28 of the prongs 24 are bent around the girdle and onto the bottom of the star facets 12 as shown in FIG. 4 so as to securely hold the diamond 10 in the setting 22.
As should be clear from the foregoing, the outer radius of the diamond defined by the girdle 16 must be slightly less than the outer radius of an imaginary circle 32 (FIG. 2B) encompassing the tips 28 of the prongs 24. Additionally, the depth of the setting 22 extending from the ledge 30 down to the common base 26 must be substantially greater than the depth of the diamond 10 as measured from the girdle 16 to the culet 20 in order to ensure that the diamond 10 contacts the setting 22 substantially only at the girdle 16 so as to ensure maximum brilliance of the stone in it setting.
As should be clear from the foregoing, the relationship between the size of the stone 10 and the setting 22 is a fairly exact one. A setting designed for a 10 point stone will at most receive a stone within one or two points of that size. When setting smaller stones, a larger number of stones are normally fitted into a single ring or other article of jewelry. These stones may all be of the same size or may be of different sizes. If of different sizes, the setter must determine the particular size stone which fits into each setting. Even if the settings are of the same size, the setter often does not know the size of the setting which is standard for a particular style ring. Even if he knows the standard size, the actual size of the settings may vary from ring to ring. For this reason, the stone setter must determine what size stone will actually fit into each setting of a given ring or other article of jewelry.
The standard method of making this determination is for the experienced diamond setter to make an educated estimate of the size of the stone which will fit into the setting and to pick up such a stone and try it in the setting. If the stone is not the right size, the stone is returned to its casing (normally an unfolded sheet of diamond paper) and another stone which has now been estimated to be of appropriate size is picked up and tried. This process is continued until the setter has determined the actual size of the setting.
Two methods are normally used to pick up the stone and size it in the setting. The first of these methods is illustrated in FIG. 5 wherein a pair of tweezers 34 are utilized to grab hold of opposite ends of the girdle 16. The diamond 10 is then placed in the setting 22 and its fit determined.
While this process will enable the setter to determine the actual size of the setting 22, it has several drawbacks. Initially, a great deal of skill is required for the setter to properly manipulate the tweezers 34 to carefully pick up the diamond 10 along the girdle 16 and securely hold the diamond 10 until it is placed into the setting 22. Even when the setter has much skill in this area, it is quite usual for him to drop a diamond which can easily damage the diamond or result in the loss of the diamond due to its small size. In addition, once the diamond has been placed in the setting, a substantial amount of care and skill is required to enable the setter to pick up the diamond using the tweezers since he must grab the girdle at a location remote from the prongs 24 of the setting 22.
In an effort to overcome some of these drawbacks, diamond setters often use a slab of clay 36 (FIG. 6) which has been formed into a cone shape, the tip of which attachs to the table 14 of the diamond 10. For ease of illustration, the slab of clay 36 is shown to be only several times larger than the diamond 10. In actual practice, the diamond 10 will be many times smaller than that illustrated in the Figure and the slab of clay 36 will be many times larger than that illustrated. If the diamond 10 is sufficiently small, the tip of the slab of clay 36 will extend over the star facets 12 and may encompass portions of the girdle 16. Since the clay is adhesive in nature, it will securely hold the diamond 10 and enable the setter to easily pick up the diamond and place it in the setting 22. The primary drawback of this method is that dirt and grease from the clay 36 will be deposited on the stone 10 with the result that the stone will be dirty when it is returned to its unfolded diamond paper packet. This necessitates preliminary cleaning of the diamonds prior to subsequent manipulation or placing them into another setting.
In order to overcome some of the deficiencies of the foregoing processes, the prior art has suggested the use of a diamond gauge which is shown, by way of illustration, in FIG. 7. As shown therein, the diamond gauge 38 includes a plurality of round openings 40 and a plurality of circular projections 42. The openings 40, as well as the projections 42, vary in size corresponding to standard diamond sizes (typically between 3 points and 4 carats). The openings 40 are utilized primarily to measure the size of diamonds 10 (the holes are placed around the diamond to determine its size) while the projections 42 are utilized to measure the size of a setting 22. A primary disadvantage of the diamond gauge 38 is that its planar structure only simulates the girdle 16 of the diamond and, therefore, provides no information as to whether the depth of the setting 22 is sufficient to receive the entire depth of the diamond 10. Thus, while the gauge 38 will provide some indication as to the radial size of the setting 22, it will not indicate whether a stone of the indicated size would actually fit into the particular setting.
Another drawback of the stone gauge 38 lies in the fact that the connecting portion 44 connecting the circular projections 42 to the base 46 of the stone gauge extends radially from the projections 42. The connecting portions 44 must be manipulated to fit in between adjacent prongs 24 which is difficult, and sometimes impossible, especially with extremely small size settings. These projections 42 also are a problem when the setting being sized is surrounded by higher settings or is otherwise recessed in a ring or other item of jewelry. With reference to FIG. 8, a setting 22 may be surrounded by gold projections 48 which form part of a highly stylized piece of jewelry. In such a case, the projections 48 prevent the connecting portion 44, and, for that matter, the base 46, of the diamond gauge 38 from being oriented in a low enough plane to permit any projection 42 to be placed within the setting 22.
While the foregoing drawbacks of the prior art methods of hand manipulating stones have been known for well over 50 years, the only solution to this problem suggested by the art is the stone gauge illustrated in FIG. 7. While several variations on this planar stone gauge have been suggested (see, for example, U.S. Pat. No. De. 162,848), all of the prior art gauges have utilized this planar structure and have, therefore possessed the foregoing disadvantages.